Radio Resource Management with a Flexible UL/DL TDD Pattern Configuration in HetNets Applied for 5th Generation of Mobile Communications
By passing 4G and moving toward the 5th generation of mobile communication, in addition to improving call quality and data rates, the variety of applications is also increasing rapidly, which leads to realization of heterogeneous networks. Heterogeneous networks are composed of conventional macro-cellular networks that include small cells such as microcells and femtosecells to increase the capacity and quality of the call. In a small cell, the uplink to downlink traffic ratio may change over time, so these small cells mainly use TDD technology instead of FDD, which makes the use of radio resources more flexible and, consequently, increases spectral efficiency. Dynamic allocation of TDD patterns for uplink and downlink is a proposed solution for traffic balancing in heterogeneous networks. But assigning different TDD patterns for each cell, results in a cross-link interference between adjacent cells, which we will discuss here with a suitable method to solve this problem.
In the first step of this thesis we implemented a small software-based LTE network using openairinterface that is capable to run on either simulation mode or radio mode by the mean of a SDR interface. It is worth mentioning that during this thesis, the emulator of the LTE network was launched at the Iranian Information and Communication Technology Institute for the first time, and its hardware and software equipment formed a dedicated LTE laboratory.
Finally, in the second step, the thesis propose a solution for Dynamic TDD suitable for small cells in heterogeneous networks, which, while taking into account the user's need for radio resources, reduced intercellular interference and, consequently, increased the signal quality and efficiency. This feature, which is deployed on the 3GPP Re-l12 LTE network, is capable of being incorporated into 5G technologies.